We’d be animals in heat avoiding pain and seeking pleasure; eating, drinking, and making merry till we die with no purpose dignity or meaning in life but ourselves. We would not realize being made in the image of God meaning we’d have no human rights as a result. What would be the purpose of life then?
The fear of the LORD is the beginning of wisdom (cf. Prov. 9:10) and also the beginning of knowledge (cf. Prov. 1:7); therefore we would be fools who knew nothing for sure, all knowledge and values relative and no absolutes. All knowledge begins in faith and is contingent.
We could realize no moral values and be completely subjective without any standards of perfection, not knowing the way to live right., as Plato said, “If I want to know how to live in reality, I must know what God is really like.” Where would we get our morals as guides? It has been said that liberty without restraint is evil and lawlessness. Who would make the rules to obey, if not the Lawgiver? No one could assume authority?
One may counter that atheists can be good moral people. But that’s like going to a restaurant enjoying the meal and denying there’s a chef. They are enjoying and reaping the benefits of centuries of Christendom and Western Civilization whether they accept it or not. God is the Lawgiver and Judge that we must be accountable to. Without hell to shun, or a Judge to fear nor Ruler to obey, we’d become quite uncivilized without the salt and light that believers bring the world.
There was a time when we had minimal perception and consciousness of God: we were pagans and barbarians living by the Iron Rule or the law of the jungle, each man for himself, and might making right. Without God in the calculus and picture, it would be a bleak outlook: coming from nothing, having no purpose, and going nowhere! IN SHORT, WE’D BE UNCIVILIZED AND IN NEED OF MISSIONARIES. Soli Deo Gloria!